Method for producing non-woven fibrous products

ABSTRACT

ING SURFACES DISPOSED IN THE PATH OF THE MATERIAL ISSUING FROM THE EXTRUSION ORIFICE.   A METHOD OF MAKING NON-WOVEN FABRICS COMPRISING SPRAY SPINNING A SUBSTANTIALLY CONTINUOUS FILAMENT OF THERMOPLASTIC POLYMERIC MATERIAL AND COLLECTING THIS MATERIAL BY MEANS OF OPPOSED SPACED-APART MOVING COLLECT-

Jim'e 12, 1973 .1. w. SOEHNGEM METHOD FOR PRODUCING NON-WOVEN FIBROUSPRODUCTS 3 Sheets-Sheet 1 Original Filed Sept. 21. 1966 June 12, 1973 J.w. SOEHNGEN 3,738,

METHOD FOR PRODUCING NON-WOVEN FIBROUS PRODUCTS Original Filed Sept. 21,1966 3 Sheefs-Sheet 2 June 12, 1973 J. w. SCEHNGEN 3,738,334

METHOD FOR PRODUCING NON-WOVEN FIBROUS PRODUCTS Original Filed Sept. 21,1966 3 Sheefis-Sheet 5 United States Paten .0"

US. Cl. 156-167 11 Claims ABSTRACT OF THE DISCLOSURE A method of makingnon-woven fabrics comprising spray spinning a substantially continuousfilament of thermoplastic polymeric material and collecting thismaterial by means of opposed spaced-apart moving collecting surfacesdisposed in the path of the material issuing from the extrusion orifice.

This application is a divisional of US. application Ser. No. 580,994,filed Sept. 21, 1966, now US. Pat. 3,607,588.

This invention relates to non-woven fibrous products and to processesand apparatus for producing such products. The invention is concernedparticularly with the provision of non-woven fibrous products ofsubstantial bulk.

Various proposals have been advanced heretofore for the formation ofsuch fibrous products as mats and the like directly from moltenfiber-forming material. In general, the fiber-forming material isextruded through orifices to form fiber and the fiber is collected onmoving belts or the like in mat form. Examples of such proposals aredisclosed in US. Pats. 2,206,058; 2,382,290; and 3,810,- 426. Thedensity of the fibrous bodies collected by these techniques, and theorientation patterns of the fiber therein, do not vary much from zone tozone across the thickness direction of the mat.

More recently improved spray-spinning processes and apparatus have beendeveloped which permit the formation of substantially continuousfilaments at high production rates and without the concurrent formationof quantities of shot and such other undesirable physical forms as veryshort fiber elements. In this connection reference is made to the patentapplication of Wagner et al. US. application Ser. No. 581,075, filedSept. 21, .1966, now abandoned, which is being filed concurrentlyherewith under the title Method and Apparatus for Producing FibrousStructures and which is owned by applicants assignee.

The present invention also is concerned with the collection ofspray-spun filamentary material in the form of fibrous bodies. However,the invention envisions the formation at a single collection station ofnon-woven fabrics in which different arrangements of the filamentarymaterial exist at different zones across the thickness direction to givethe fabrics distinctive properties.

More particularly, it is an object of this invention to provide novelnon-woven fibrous structures having spacedapart surface layers ofsubstantial density and having an integrally formed core made up offibrous components bridging the space between the surface layers.

Another object of the invention is to provide non- Woven pile-likefabrics characterized by the presence of a backing layer and integrallyformed fibrous components protruding upwardly from the backing layer.

Other objects of the invention include the provision of novel processesand apparatus for producing these fabrics economically and reliably.

The invention may be used in connection with the production of productsfrom any of the various materials that may be melted and extrudedthrough an orifice to 3,738,884 Patented June 12, 1973 form a filament.Examples of suitable types of fiber-forming materials are polyolefins,polyamides, polyesters, cellulose acetate, polyvinyl acetate,poly(methyl methacrylate) styrene copolymers, and glass.

In accordance with a preferred embodiment of the invention, asubstantially continuous filament of thermoplastic polymeric material isformed by the spray spinning techniques disclosed in the aforesaidpatent application of Wagner et al. and collected by means of opposedspaced-apart, contrarotating rolls disposed in the path of the materialissuing from the extrusion orifice. The gap between the two rolls issubstantial, and only portions of the spray-gun filamentary material aredeposited directly upon the roll surfaces. The remainder of thefilamentary material crosses back and forth randomly between the layersof material deposited on the roll surfaces to form a bridging structureconnecting the layers together. j i 1 Some bonding together of thefilament sections ordinarily is desirable. For example, the rolls may belocated close enough to the spray spinning nozzle to receive thefilamentary material while surface portions of the filament sections aresufficiently tacky to permit a degree of self bonding at crossoverpoints.

.As the rolls rotate, the collected filamentary material is removed fromthe collection zone in the form of a non-woven fabric having surfacelayers in which the fiber components are generally parallel to thefabric surfaces and having an interior core in which the fibercomponents extend at angles to the surfaces. The relative thicknesses ofthe different fabric zones may be regulated by suitable adjustment ofsuch factors as the gap between the rolls, the spacing of the rolls fromthe spray spinning nozzle and the speed of rotation of the rolls. Inproducing the high bulk products of this invention, it ordinarily isdesirable that the individual surface layers have a thickness no greaterthan one-third of thickness of the product. More preferably, each of thesurface layers should have a thickness less than one-sixth of the totalfabricthickness, leaving over half of the fabric thickness to be takenup by the bridging structure constituting the interior core.

In accordance with another aspect of the invention, fibroussubassemblies contributing significantly to the overall fabricproperties may be formed during the collection of the spray spunfilamentary material. In one embodiment for example, the collector rollsare traversed laterally back and forth in front of the spinning nozzlein such a manner as to produce during each traverse a generally U-shapedsheet the ends of which are adjacent the roll surfaces and the centralportion of which bridges the gap between the rolls. As the traversingcontinues, the successively collected U-shaped sheet-like units arecombined into a non-woven fabric in which overlapping and contacting endportions of a number of the U-shaped sheets are consolidated as surfacelayers or skins and in which the central bridging portions of adjacentsheets are spaced apart from each other to provide a resilient coreformed integrally with the surface layers.

In another embodiment, a plurality of spray spinning nozzles arearranged to project filamentary material toward the gap between theopposed collection surfaces of a single collector unit. The spraypatterns from adjacent nozzles overlap in the collection zone so that aunitary product will be formed even though the filamentary materialissues from different sources. Set-ups of this type are particularlydesirable in producing fabrics having zones of different characteristicsacross the width thereof and in producing wide fabrics without thesheet-like subassemblies which sometimes are formed when a traversemotion is employed.

The invention also contemplates the production of pilelike non-wovenfabrics. The fibrous body removed from the collection zone through thegap between the opposed collector surfaces may be severed or slitlengthwise at a level between the surface layers deposited on thecollector surfaces to provide two fabrics in each of which the surfacelayer serves as a backing and the attached portion of the bridgingstructure projects upwardly from the backing. The nature of theupstanding material or pile will depend of course upon the conditionsmaintained during collection of the spray spun fiber, and a variety ofeffects can be achieved. For example, the upstanding material on thesurface of the fabric may be thin sheet-like subassemblies formingtransversely extending leaves. This particular effect is achieved byslitting an assembly collected on a set-up having a traverse motion, andoperating as described above to produce a series of thin, generallyU-shaped, sheet-like subassemblies as the spray pattern moves laterallyback and forth across the collector surfaces.

A more complete understanding of these and other features of theinvention will be gained from a consideration of the followingdescription of certain embodiments illustrated in the accompanyingdrawings, in which:

FIG. 1 is a schematic elevational view depicting one form of apparatussetup that may be used in practicing the invention; 7

FIG. 2 is a face view of the collector roll assembly shown in FIG. 1;

FIG. 3 is a top view of an apparatus setup similar to that illustratedin FIG. 1 but having a plurality of spray spinning nozzles associatedwith a single collector unit;

FIG. 4 is an elevational view depicting another form of collectorstructure and also illustrating the formation of pile-like non-wovenfabrics in accordance with the invention;

FIG. 5 is a schematic top view of another embodiment of the invention inwhich the collector unit is traversed bodily back and forth in front ofthe spray spinning means;

FIG. 6 is a diagrammatic view of the fibrous sub-assemblies producedduring traverse motions of the collector unit of the apparatus of FIG.5; and

FIG. 7 is a photograph showing in longitudinal cross section thenon-woven fabric produced through use in accordance with the inventionof the apparatus of FIG. 5.

Spray spinning nozzle means are indicated schematically at 2 in FIG. 1.Preferred nozzle structures are disclosed in the aforesaid patentapplication of Wagner et al. and for detailed information on thesestructures reference should be made to such application. It will besufficient to point out here that the preferred spray spinning nozzle isprovided with an orifice through which the molten fiber-forming materialis extruded and is also provided with a plurality of gas passagesdisposed about the axis of the extrusion orifice. The gas passages areinclined to direct heated gas, such as steam, along paths the axes ofwhich converge toward but do not intersect the projected axis of theextrusion orifice. The high velocity gas streams issuing from the gaspassages attenuate the filament extruded through the extrusion orificeand project the filament away from the nozzle in a random swirlingpattern.

The collector unit depicted in FIG. 1 includes a pair of opposed,spaced-apart rolls 4 and 6 mounted for rotation in a suitable frame andhaving smooth surfaces. The rolls 4 and 6 are spaced a predetermineddistance from the nozzle 2, and the gap between the rolls is insubstantial alignment with the central axis of the nozzle 2.

The filament 8 is projected in a generally longitudinal direction fromthe nozzle 2, but increments thereof deviate randomly from the extrusionorifice axis due to the high filament velocity and the effects of thegas issuing from the nozzle. The overall result is a spray pattern that4 is generally conical in outline as indicated schematically at 9 inFIGS. 1 and 2.

In establishing the proper spacial relationship between the nozzle 2 andthe collector unit, consideration should be given to the shape and sizeof the spray pattern 9 in the collection zone. As indicated in FIG. 2,the diameter of the spray pattern 9 should be greater than the gapbetween the surfaces of the collection rolls 4 and 6. When thisrelationship exists, portions of the projected filamentary material willbe deposited directly upon the surfaces of the rolls 4 and 6 and otherportions will be swirled about randomly to bridge the gap between therolls.

The extent to which the freshly-spun filamentary material hardens priorto collection also is affected by the spacing between the nozzle 2 andthe collection unit. Ordinarily, it is desirable that collection takesplace while the surfaces of the filamentary material are stillsufiiciently tacky to effect self-bonding as between filament sectionsat crossover points. If other factors be held constant, the degree ofself-bonding may be varied by changing the distance from the nozzle 2 tothe collection rolls 4 and 6. Control over the degree of self-bondingachieved may also be exercised by regulation of the extrusiontemperature at the nozzle 2 and/or by heating or cooling the surfaces ofthe collection rolls 4 and 6.

In instances where supplemental fiber-to-fiber bonding may be desired,suitable binders and/or plasticizers may be employed. For example,compositions compatible with the fiber-forming material may be added tothe melt supplied to the extrusion orifice, or spraying techniques maybe used to apply suitable compositions to the filamentary materialeither in the zone of collection thereof or at a subsequent stage of theprocess.

As the collection rolls 4 and 6 are rotated in the directions indicatedby the arrows in FIG. 1, the collected filamentary material is removedfrom the collection zone through the gap between the rolls in the formof a nonwoven fabric product 10. Any suitable drive means may beemployed for rotating the rolls 4 and 6. In FIG. 2 the drive means hasbeen shown as including a motor 11, gear means 12 coupling the motor 11to the shaft of roll 6, and gears 13 coupling together the rolls 4 and 6for rotation at the same speed but in opposite directions.

The non-woven fabric 10 has a distinctive structure. This structureincludes upper and lower surface layers 14 spaced apart by an integrallyformed core 15. The surface layers 14 are made up of the fiber depositedupon the smooth surfaces of the collector rolls 4 and 6, and in theselayers the predominant orientation of the filamentary material isparallel to the surface of the product 10. However, a significantlydifferent orientation exists in the core 15. The fiber components hereare those that were collected as bridging units extending across the gapbetween the collector rolls 4 and 6, and their predominant orientationis at an angle to the faces of the product 10.

The density characteristics of the zones 14 and 15 also are different.In the surface layers 14 the filamentary components are packed closelytogether. The bridging portion 15, however, is in the form of a networkhavimx substantial open spaces between fibrous componer The thickness ofthe fabric 10 is determined by the spacing between the collector rolls 4and 6. Normally it will be found desirable to mount the rolls so as topermit ad ustment of their relative positions, so that fabrics ofdifferent thicknesses may be produced. The gap between the opposedsurfaces of the rolls 4 and 6 should be in the range of from aboutone-eighth inch to about four inches in thickness, and more preferablywithin the range from about one-half inch to about two inches.

Although a single spray spinning nozzle is indicated in FIG. 1, the useof a plurality of such nozzles is preferable in some instances. Such anembodiment of the invention is illustrated in FIG. 3. This embodimentincludes a plurality of spray nozzles 16 disposed in alignment with thegap between a single pair of opposed collector rolls 18. The rolls aremounted in a frame 20. A motor 22 on the frame drives a belt 24, whichpasses over a pulley on the end of the shaft for the lower roll 18, andthe shaft for the upper roll 18 is connected with the lower roll by across belt 26. Thus, the rolls 18 rotate in opposite directions when themotor 22 is operating.

The positional relationships between the several nozzles 16. are suchthat the spray patterns 30 from adjacent nozzles overlap in thecollection zone. With this arrangement, a wide non-woven fabric 32 isproduced during operation of the equipment. This fabric 32 is similar tothe fabric described above in connection with FIG. I inthe sense that itis made up of surface layers connected together by bridging fibercomponents. In the widthwise direction the fabric 32 may besubstantially uniform from zone to zone across the fabric or it may becharacterized by zones that are different from one another.

Transverse uniformity is achieved when the overlap between the spraypatterns from adjacent ones of the nozzles 16 is sufiicient to assuredelivery of substantially the same amount of filamentary material to allportions of the collector zone. On the other hand, Where densityvariations in the transverse direction are desired, the overlap betweenadjacent spray patterns from the nozzles 16 may be such as to cause thedelivery of filamentary material to one portion of the collector to begreater than the delivery of filamentary material to another portionthereof.

Still other effects may be achieved in the embodiment of FIG. 3 bysupplying fiber-forming materials having different characteristics tovarious ones of the several nozzles 16, and/or by using nozzles havingextrusion orifices of different sizes or different rates of delivery.The spray patterns of several nozzles 16 may overlap to the extent ofintermingling filaments during formation of the mat or fabric. Differentmaterials may be sprayed simultaneously from the nozzles to produce afabric having a uniform dispersion of filaments of different materials.The nozzles may be arranged along an axis perpendicular to the widthdimension of the gap between the collector rolls, or any other suitablearrangement of nozzles may be used. By arranging a plurality of nozzles,side by side along an axis parallel to the width of the gap, a non-wovenfabric 32 may be produced that is characterized by the presence oflongitudinally extending portions or stripes having different visual orstructural properties. For example, in some applications for the highbulk non-woven fabrics of this invention it is desirable that thefabrics be provided with a defined flex-zone susceptible of being bentmore readily than other portions of the fabric. Such a zone can beformed by spray spinning from one of the nozzles 16 filamentary materialof significantly smaller average denier than the filamentary materialissuing from the other nozzles 16.

Although the collector units in the embodiment described above have beenshown as including opposed rolls having smooth surfaces, it will beunderstood that the invention is not limited to this particular form.Suitable collector surfaces may be provided by endless belts, webs orthe like, and the collector surfaces may be rough or provided withprotruding portions or embossed patterns. Also, laminated products maybe formed by collecting the filamentary material directly upon sheets orwebs passed over one or both of the collector rolls and causing thefilamentary material to adhere to such sheets or webs, as by heating orbonding treatments.

In the embodiment illustrated in FIG. 4, an endless belt 34 is mountedover rolls 36 and 38 and over an idler roll 40 which supports theintermediate portion of the belt 34. An opposing belt 42 is mountedbetween the rolls 44 and 46 and passes over an idler roll 48. Presserrolls 49 are mounted adjacent the idler rolls 40 and 48 in 6 position tobear against and guide the exterior surfaces of the belts 34 and 42.

A spray spinning nozzle 50 corresponding to the nozzle 2 in FIG. 1 ispositioned opposite the gap between the belts 34 and 42 in the zone ofthe rolls 36 and 44. Collection of the filamentary material issuing fromthe nozzle 50 takes place in much the same manner as in FIG. 1. Portionsof the filamentary material are deposited directly upon the surfaces ofthe belts 34 and 42 and other portions bridge back and forth across thegap. As the rolls rotate in the directions indicated by the arrows, thecollected material is removed from the collection zone in the form of anon-woven fabric structure.

In the area between the front rolls 36 and 44 and the idler rolls 40 and48, the fiber contacting flights of the belts 34 and 42 aresubstantially parallel. These surfaces maintain the newly formednon-woven fabric to the dimension of the gap and serve to minimize themechanical loads imposed on the material.

The non-woven fabric product delivered by the belts 34 and 42 in thezone of the idler rolls 40 and 48 is similar to the product 10 producedas described in connection with FIG. 1, and this product may be used assuch if desired. However, FIG. 4 illustrates an additional operationthat may be carried out in forming other novel products in accordancewith the invention. Severing means 52 is disposed between the belts 34and 42 just beyond the idler rolls 40 and 48. This severing means 52 maybe in the form of a stationary cutter blade, a reciprocating saw orblade, a band saw, or other suitable fiber severing device.

The level of the severing means 52 is such that it contacts the fibercomponents bridging the vertical space between the surface layers of thefibrous body being advanced by the belts 34 and 42. The severance ofthese bridging components across the entire width of the body yields twoseparate fabrics 54. These move with the diverging flights of the belts34 and 42 in the zone between the idler rolls 40 and 48 and the backrolls 38 and 46, and they are individually guided away by suitable means55 for separate collection.

Each of the non-woven fabrics S4 is pile-like in character. The surfacelayer of the filamentary material deposited on one of the belts of thecollector constitutes a firm backing structure 56, and the severedportion 57 of the bridging fiber components extends from the backing inflexible pile-like configurations. These non-woven pile; like fabricsmay be produced economically and they are suitable for use in many ofthe environments where conventional pile fabrics have been employedheretofore.

In producing these pile-like fabrics it is not essential that abelt-type collector unit be employed. Apparatus having roll-typecollector units as shown in FIGS. 1-3 can be used for the production ofpile fabrics by disposing suitable severing means downstream of the gapbetween the rolls. Generally, however, it will be found preferable toutilize a belt-type collector, because belts such as those shown at 34and 42 in FIG. 4 provide relatively large surface areas for frictionallyadvancing the fibrous assembly against the severing means 52.

Still other aspects of the invention are illustrated in connection withFIGS. 5-7 of the drawings. FIG. 5 illustrates schematically an apparatussetup in which relative lateral movement is effected as between sprayspinning nozzle means and a collector unit.

A pair of opposed collector rolls 58 are disposed in front of sprayspinning means 60, with the spray pattern 62 from the nozzle 60intersecting the gap between the rolls 58. The rolls 58 are mounted forrotation in a frame 64, and the frame 64 is carried by rails 66. Therolls 58 are relatively long, as compared with the diameter of the spraypattern 62 at the collection zone. However, the frame 64 is shifted backand forth along the rails 66 to position different portions of the rollsurfaces in the path of the filamentary material issuing from the nozzlemeans 60.

The traversing motion of the rolls 58 may be accomplished through theuse of any suitable drive means. In FIG. the drive means has beenillustrated as including a link 68 pivotally connected at one of itsends to a pin 70 projecting from a belt 72 and at its other end to abracket 74 on the frame 64. The belt 72 is disposed beneath the level ofthe frame 64 and is trained about rolls 76 and 78. The roll 78 is drivenfrom a motor 80 through suitable coupling means such as a belt 82. Uponoperation of the motor 80, the roll 78 is rotated to move the belt 72through an endless path. As the pin 70 moves along the belt path, theframe 64 traverses back and forth along the rails 66 in front of thenozzle 60.

In this embodiment, it is preferred that a substantial degree of bondingat crossover points between contacting filament sections be achieved inthe collection zone. This normally presents no difficulty because itusually is feasible to regulate the extrusion temperature and/or thespacing between the nozzle 60 and the collector rolls 58 so that thefilamentary material reaches the collection zone while surface portionsthereof are still sufficiently tacky to permit self-bonding at crossoverpoints. However, a suitable binder or plasticizer composition may besprayed into the collection zone along with the filamentary material ifdesired.

As the zone of intersection between the spray pattern 62 from the nozzle60 and the collection rolls 58 shifts back and forth across the width ofthe collection unit, a series of thin sheetlike fibrous subassemblies 84are formed. Each of the subassemblies is generally U-shaped inconfiguration, as suggested in FIG. 6, and within each sheet thefilament is randomly arrayed in the sense that, if the U-shapedsubassembly were flattened into a plane, incremental portions of thefilament would be found extending in substantially all directions withinthat plane.

Of course, the U-shaped subassemblies 84 formed on successive traversesof the collector units are not entirely separate from each other. At theend of one traversing motion and the beginning of the next traversingmotion, only a single body of filamentary material is collected, so thatsuccessive ones of the subassemblies 84 actually are united at thelateral margins of the fabric. This effect ordinarily is a desirableone, but in those instances where a high degree of widthwise productuniformity is required, the lateral margins of the fabric may be trimmedoff.

The upper and lower end portions 86 of adjacent U- shaped subassembliesoverlap substantially. These are interentangled somewhat and are packedtogether to form the surface layers at the top and bottom of the productcollected. Portions of at least three and preferably five or more of thesubassemblies 84 should be present at any given vertical cross sectionthrough one of the surface layers. In these surface layers, the fibercomponents are generally parallel to the faces of the fabric.

The mid-portions 88 of adjacent ones of the U-shaped subassemblies 84are spaced apart from each other. This effect is indicated in FIG. 6 andin the photograph designated FIG. 7. The amount of the spacing issubject to variation, depending upon the characteristics desired in theproducts produced. Control over the spacing between the mid-portions 88of successive U-shaped subassemblies 84 may be effected by suitableregulation of the surface speeds of the collector rolls 58 in relationto the rate of traverse of the rolls along the rails 66.

The mid-portions 88 of the subassemblies extend at angles to the facesof the non-woven fabrics. Thus, although the fiber components arerandomly arrayed within the individual subassemblies 84, the non-Wovenfabric as a whole exhibits different fiber orientations in differentzones across the thickness of the fabric. That is to say, thepredominant orientation of the fiber components in the surface layers isparallel to the faces of the fabric, while the predominant fiberorientation in the middle of the fabric is at an angle to the fabricfaces. This angle varies, of course, from 90 on down as one follows aU-shaped 8 subassembly from its mid-point toward a surface layer of thefabric.

Fabrics of the type illustrated in FIG. 7 may be used as such or theymay be subjected to further treatments. Particularly interesting resultsmay be obtained, for example, by slitting a fabric of this type throughthe midportions 88 of the U-shaped subassemblies. This slitting actionmay be carried out as described above in connection with FIG. 4.

Each of the two fabrics resulting from the slitting operation ischaracterized by a base or backing structure having a plurality ofleaf-like assemblies of fiber components protruding therefrom. Theleaf-like bodies may be flexed independently of each other in a mannersomewhat analogous to that of the pile of pile fabrics of a moreconventional nature. However, the transverse continuity of the leavesgives these fabrics structural properties not heretofore attainable.

An example will serve to further illustrate the invention. This exampleoutlines conditions used in the production of a non-woven fabric adaptedto be employed as a pad under a carpet.

EXAMPLE Polypropylene pellets (Hercules Pro-fax 6423) were fed to aModern Plastics Machinery extruder (1" x 24") having three zonesmaintained at 205 C., 275 C. and 335 C., respectively, and extrudedthrough a nozzle having a circular orifice of 0.028 inch diameter at amaterial temperature of about 332 C. The nozzle included three 0.082inch ports disposed annularly about the orifice, directing streams ofsteam along paths the axes of which converged toward but did notintersect the extended axis of the extrusion orifice, the closest pointto convergence lying about 1 inch from the orifice. The steam had a linepressure of 16 p.s.i.g. and a temperature of 410 C.

The ports were spaced about apart and the axes were arranged to providean opening of about inch in diameter therebetween at the point ofclosest convergence, through which the extrudate passed. The extrudatewas thereupon attenuated and whipped about with little or no breakage,and taken up While still at least tacky and capable of self-bonding at apoint 8 /2 inches from the die orifice on a pair of rolls of 4 inchdiameter, counterrotating at about 0.11 r.p.m. and providing a /2 inchnip therebetween through which the material passed in a band of about 3inches width.

About 1 lb./hr. of material was extruded and taken up as about a 25oz./yd. batting containing principally endless continuous filamentranging in diameter from about 15 to about 55 microns with the changesin diameter having a relatively long period on the order of severalinches. The average diameter was about 24 microns, indicating somepreponderance of the lower diameters.

The resulting fabric had the firmness, deformability and resiliencequalities required of carpet underlayments.

Of course, in normal production operations it is desirable to producecarpet padding material in wide strips. A suitable carpet underlay maybe provided as 4 x 8 foot sheets or as a continuous matting of e.g., 9feet width rolled about 4 to 6" cores, by utilizing a multiplicity ofspray nozzles or traversing the take-up surface. The underlayment mayalso be sprayed directly onto a carpet backing with a suitable binder ormay even constitute the secondary backing itself. Such an embodiment isparticularly desirable where the carpet backing comprises a similarsynthetic polymer such as polypropylene as in the woven form describedin US. Pat. 3,110,905.

The products of this invention are suitable for many other uses. Sincethe bulky structures are produced directly from an extrusion operation,they are relatively inexpensive. Furthermore, the structures produced inaccordance with this invention do not necessarily contain any adhesiveand therefore may be more resistant to solvent action than conventionalnon-woven fabrics. The

unsevered fabric may be used for insulation, ceiling tile, air filtersand other articles. The pile-like structures produced from the severedfabric may be used for low cost floor covering, in clothing apparel, andother articles.

While this invention has been illustrated and described in severalembodiments, it is recognized that variations and changes may be madetherein without departing from the invention as set forth in the claims.

What is claimed is:

1. A method of making non-woven fabrics comprising extruding meltedthermoplastic material to form a substantially continuous filament,projecting said filament in a longitudinal direction and in a randomswirling pattern toward a gap between an opposed pair of spaced-apartmoving collecting surfaces; and collecting the filamentary material in azone extending across the path of the projected filament and partiallyoccupied by convergent portions of the pair of moving collectionsurfaces so oriented with respect to each other as to leave a gaptherebetween, the filamentary material being collected in the form ofspaced-apart first and second surface layers respectively adjacent saidcollection surfaces and bridging portions between said layers, with thesubstantially continuous filament passing randomly through said surfacelayers and bridging portions.

2. The process according to claim 1 including moving said collectionsurfaces toward said gap at a uniform rate.

3. The process according to claim 1 including projecting a secondthermoplastic, substantially continuous filament in a longitudinaldirection spaced laterally from but generally parallel to saidfirst-mentioned filament and in a random turbulent pattern overlapping aportion of said first-mentioned filament.

4. The process according to claim 3 wherein said secnd filament hasdifferent characteristics from those of said first-mentioned filament.

5. The process according to claim 2 including reciprocally displacingsaid filament pattern laterally along said gap whereby a fabric having agreater width than said pattern is produced.

6. The process according to claim 5 wherein said displacing isaccomplished by reciprocating said collection surfaces laterallyrelative to said filament pattern along said gap.

7. A process for making a non-woven fabric comprising spray spinningthermoplastic filamentary material toward a gap between an opposed pairof spaced apart collectors,

depositing on one of said collectors a first layer of closely packedfilamentary material having a thickness no greater than one-third thewidth of the gap between the collectors,

depositing on the other of said collectors a second layer of closelypacked filamentary material having a 10 thickness no greater thanone-third the width of the gap between the collectors, and

collecting the remaining filamentary material between said first andsecond layers in the form of a core in which the filamentary material isless closely packed than in said first and second layers.

8. The process according to claim 5 wherein said filamentary material insaid first and second layers is deposited generally parallel to thesurfaces of the respective layers, and said filamentary material betweensaid layers is generally inclined relative to the surfaces of saidlayers.

9. The process according to claim 7 wherein said filamentary materialcontacts said surfaces in a pattern extending across said gap, andincluding reciprocally displacing said pattern later-ally along said gapto produce a fabric having a width greater than said pattern.

10. A process for making non-woven fabrics comprising extruding meltedthermoplastic material through an orifice to form a substantiallycontinuous filament stream, directing a plurality of high velocity gasstreams generally longitudinally of said filament stream, to attenuatethe filament stream and causing a swirling movement of said filamentstream about the axis of said orifice,

collecting said filament stream on a pair of surfaces defining a gaptherebetween, said filament stream being deposited on said surfaces inthe form of surface layers joined together by continuous filamentportions between said layers, and

advancing said surfaces in a direction away from said orifice to drawfilament portions collected on said surfaces through said gap whilemaintaining said gap at a greater thickness than the combined thicknessof said surface layers whereby a continuous fabric is formed having acenter portion with a lower density of filament portions than in saidlayers.

11. The process according to claim 10 including severing said fabricbetween said surface layers, and separating said severed mats to form anon-woven fabric having randomly oriented upstanding filament portionson one side.

References Cited UNITED STATES PATENTS 3,509,009 4/1970 Hartmann 156-l8l3,505,155 4/1970 Balch et al. 156--181 3,423,266 1/ 1969 Davies et a1.156181 3,314,840 4/ 1967 Lloyd et al. 156167 3,511,742 5/1970 Rasmussen161-409 3,010,508 11/1961 Wilson et al. 156-254 DANIEL J. FRITSCH,Primary Examiner US. Cl. X.R.

